Use tracking information from video to make a 2d panorama
The only way to achieve this in Blender I think is with Dynamic Paint. But the vertex paint can be poor quality. You'll have to bake an image sequence. Of course you only need the last frame.


Track the image with 1 marker. Use "offset" if marker leaves frame.





Solve the track for Tripod.
In Geometry tab of the MCE link an empty to the track.
Go to the 3D view and create a plane for the canvas, subdivide it
lots. The more you subdivide it the sharper the image later.
Give it a Copy location Constraint (new empty)and a copy rotation
constraint (camera rotation).
Press 0 to look through the camera and scale the canvas so that it
covers the camera view from first frame to last.
Then add another plane using the Images as Planes addon. This will
be the brush.
Give it a constraint to copy the camera location but in edit mode,
scale it to fill the field of view and move it towards the canvas
object.
Add a Solidify modifier so that the image plane goes through the
canvas plane.





Go to the physics tab and activate Dynamic paint > brush. Set
 material to the movie image material.
Now select the canvas and in the physics tab activate the Dynamic
 paint > canvas. Turn down Drying time to 1 frame.




The canvas should move below the camera in sync with the original camera move. The source movie should be projected onto the canvas from the camera point of view.

To reduce the processing you would use fewer frames from the source pan. Blender won't drop frames in Texture mode so you would have to preprocess them in the VSE, by applying a speed effect which will drop frames. In this way a pan that could use 100 frames could be created with just 10 frames. Tracking would be a bit more challenging.